More than likely he was in shock due to numerous issues that could have happened when he was put in the tank. Drastic change in temp, ph, salinity, etc. Luckily they are hardy fish and can take the abuse (not that they should or that you meant to). Go ahead and get some more 'Cured' live rock if you can. If your not sure if it is cured, just put it in a small rubbermaid tube with am airstone or PH to circulate the water and cure it. For a 10, it is recommended to have 10-15 lbs of rock.
What type of sand are you using?
Most important now is to test the water daily (if not twice), and do a small water change each time to try to prevent a bad ammonia spike.
Also, I would only feed a little every 3 days for the time being to help keep the ammonia at bay. Once you've cycled, increase to every other day.
Check your salinity everyday at least and top it off if it starts to rise with RODI water. The fish is going to go through a little more stress more than likely, just try to limit it as much as possible.